Accurate Source-Receiver Positioning Method for a High-Resolution Deep-Towed Multichannel Seismic Exploration System

The near-seabed multichannel seismic exploration systems have yielded remarkable successes in marine geological disaster assessment,marine gas hydrate investigation,and deep-sea mineral exploration owing to their high vertical and horizontal resolution.However,the quality of deep-towed seismic imaging hinges on accurate source-receiver positioning information.In light of existing technical problems,we propose a novel array geometry inversion method tailored for high-resolution deep-towed multichannel seismic exploration systems.This method is independent of the attitude and depth sensors along a deep-towed seismic streamer,accounting for variations in seawater velocity and seabed slope angle.Our approach decomposes the towed line array into multiline segments and characterizes its geometric shape using the line segment distance and pitch angle.Introducing optimization parameters for seawater velocity and seabed slope angle,we establish an objective function based on the model,yielding results that align with objective reality.Employing the particle swarm optimization algorithm enables synchronous acquisition of optimized inversion results for array geometry and seawater velocity.Experimental validation using theoretical models and practical data verifies that our approach effectively enhances source and receiver positioning inversion accuracy.The algorithm exhibits robust stability and reliability,addressing uncertainties in seismic traveltime picking and complex seabed topography conditions.

Non-PLL high-precision synchronous sampling method among lots of acoustics acquisition channels for underwater multilinear array seismic exploration system

Synchronous sampling is very essential in underwater multilinear array seismic exploration system in which every acquisition node(AN)samples analog signals by its own analog-digital converter(ADC).Aiming at the problems of complex synchronous sampling method and long locking time after varying sampling rate in traditional underwater seismic exploration system,an improved synchronous sampling model based on the master-slave synchronous model and local clock asynchronous drive with non phase locked loop(PLL)is built,and a high-precision synchronous sampling method is proposed,which combines the short-term stability of local asynchronous driving clock with the master-slave synchronous calibration of local sampling clock.Based on the improved synchronous sampling model,the influence of clock stability,transmission delay and phase jitter on synchronous sampling error is analyzed,and a high-precision calibration method of synchronous sampling error based on step-by-step compensation of transmission delay is proposed.The model and method effectively realize the immunity of phase jitter on synchronous sampling error in principle,and compensate the influence of signal transmission delay on synchronous sampling error.At the same time,it greatly reduces the complexity of software and hardware implementation of synchronous sampling,and solves the problem of long locking time after changing the sampling rate in traditional methods.The experimental system of synchronous sampling for dual linear array is built,and the synchronous sampling accuracy is better than 5 ns.

On electro-acoustic characteristics of a marine broadband sparker for seismic exploration

The construction of major marine infrastructure projects and the exploration and development of deep-sea mineral resources require fine imaging of seabed strata and structures.The highresolution marine seismic exploration based on a high broadband sparker source is an important approach to reveal seabed stratum and reservoir structure,and identify geohazard.To optimize the performance of sparker seismic source,we investigated the electro-acoustic characteristics of spark discharge under conditions of different charging voltages and electrode numbers.Results show that the sound source level increased with the increase of the charging voltage,whereas the main frequency decreased when the charging voltage increases.In addition,it was found that the charging capacitance had more obvious influence on the main frequency than the sound source level did.Although the load energy decreased with increasing electrode number,the sound source level still increased but the main frequency decreased.Meanwhile,the primary to bubble(P/B)ratio increased with the increase of the electrode number.To gain a deeper insight into the electro-acoustic characteristics,we investigate the relationship between sound source level and power peak,from which a good correlation was observed.A more practical statistical analysis on the rise rate of current was processed,and a perfect logarithmic function was derived.Furthermore,we found that the main frequency was most possibly subjected to the electrical energy,especially the charging energy per electrode.The results indicate that the charging energy per electrode less than 10 J could increase the main frequency to above 300 Hz.At last,the main frequency could be reduced to 20 Hz when the charging energy of a single-electrode discharge was enhanced to over 4 kJ.This study shall be helpful in developing a sparker seismic source and improving the performance for marine engineering exploration and geohazard assessment.

Field Test Summary of Two Kinds of Electronic Detonator for Seismic Exploration

Electronic detonators are widely used because of their advantages in real-time supervision of the whole life cycle (Zang, 2022). Due to the high requirements of the time difference synchronization between the electronic initiation system and the seismic wave recording system, the Electronic detonator has not been widely used for Seismic exploration (Yang, 2020). This paper expounds the systematic and scientific test method from the aspects of the comprehensive performance of electronic detonators for exploration, the compatibility between the electronic detonator initiation system and the geophysical blasting machine system, the constraints of the geophysical explosion-related collaborative Danling managment cloud platform, and the quality of data collected by electronic detonator blasting in wells., and based on the analysis of the test results, the problems that need to be improved in the application of electronic detonators and detonation systems in the large-scale production of geophysical prospecting industry are put forward. .

Application Results of 3-D Seismic Exploration Technology in Coal Mines

This paper briefly introduces the development and present situation of China's coal seismic exploration. It focuses on analyzing the important functions of 3-D seismic exploration technology in the designing and production of coal mines, and also the results of its application.

Preface to the Special Issue on Advances in Seismic Exploration and Monitoring with Active Sources in China

Analyzing the information carriede by seismic waves is a major means for human beings to have an insight into the structure of the earth’s interior,and by using artificial seismic sources to excite seismic waves,we can obtain high-resolution images for the crustal and smaller scale medium.Artificial seismic exploration methods have been widely applied to fields such as

Inverse gaussian beam stack imaging in 3D crosswell seismic exploration of deviated wells and Its application

In crosswell seismic exploration,the imaging section produced by migration based on a wave equation has a serious arc phenomenon at its edge and a small effective range because of geometrical restrictions.Another imaging section produced by the VSP-CDP stack imaging method employed with ray-tracing theory is amplitude-preserved.However,imaging 3D complex lithological structures accurately with this method is difficult.Therefore,this study proposes inverse Gaussian beam stack imaging in the 3D crosswell seismic exploration of deviated wells on the basis of Gaussian beam ray-tracing theory.By employing Gaussian beam ray-tracing theory in 3D crosswell seismic exploration,we analyzed the energy relationship between seismic wave fields and their effective rays.In imaging,the single-channel seismic wave fi eld data in the common shot point gather are converted into multiple effective wave fields in the common reflection point gather by the inverse Gaussian beam.The process produces a large fold number of intensive reflection points.Selected from the horizontal and vertical directions of the 2D measuring line,the wave fi elds of the eff ective reflection points in the same stack bin are projected onto the 2D measuring line,chosen according to the distribution characteristics of the reflection points,and stacked into an imaging section.The method is applied to X oilfi eld to identify the internal structure of the off shore gas cloud area.The results provided positive support for the inverse Gaussian beam stack imaging of 3D complex lithological structures and proved that technology is a powerful imaging tool for 3D crosswell seismic data processing.

Full wave seismic exploration technology

Reflected wave seismology has the following defects:the acquisition design is based on the assumption of layered media,the signal processing suppresses weak signals such as diffracted wave and scattered wave,and the seismic wave band after the image processing is narrow.They limit the full utilization of broadband raw data.The concept of full wave seismic exploration is redefined based on the idea of balanced utilization of reflected wave,diffracted wave and scattered wave information,its characteristics and adaptive conditions are clarified.A set of key technologies suitable for full wave seismic exploration are put forward.During seismic acquisition period,it is necessary to adopt multi geometry,i.e.embed small bin,small offset and small channel interval data in conventional geometry.By discretizing of common midpoint(CMP)gathers,small offset with high coverage,the weak signals such as diffracted wave and scattered wave in the raw seismic data can be enhanced.During seismic processing,the signal and noise in the original seismic data need to be redefined at first.The effective signals of seismic data are enhanced through merging of multi-geometry data.By means of differential application of data with different bin sizes and different arrangement modes,different regimes of seismic waves can be effectively decomposed and imaged separately.During seismic interpretation stage,making the most of the full wave seismic data,and adopting well-seismic calibration on multi-scale and multi-dimension,the seismic attributes in multi-regimes and multi-domains are interpreted to reveal interior information of complex lithology bodies and improve the lateral resolution of non-layered reservoirs.

New Progress in High-Precision and High-Resolution Seismic Exploration Technique in Coal Industry of China

In the past twenty years, the proportion of coal in primary-energy consumption in China is generally between 71.3% and 76.5%. The output of coal was 1.374 billion tons in 1996, and 1.21 tons in 1998, which ranked first in the world. Now coal is mined mainly with mechanization in China, which is planned to reach 80% in major State-owned coal mines in 2000 according to the planning of the government (Li et al., 1998; Tang Dejin, 1998).

Applying Non-Local Means Filter on Seismic Exploration

The seismic reflection method is one of the most important methods in geophysical exploration.There are three stages in a seismic exploration survey:acquisition,processing,and interpretation.This paper focuses on a pre-processing tool,the Non-Local Means(NLM)filter algorithm,which is a powerful technique that can significantly suppress noise in seismic data.However,the domain of the NLM algorithm is the whole dataset and 3D seismic data being very large,often exceeding one terabyte(TB),it is impossible to store all the data in Random Access Memory(RAM).Furthermore,the NLM filter would require a considerably long runtime.These factors make a straightforward implementation of the NLM algorithm on real geophysical exploration data infeasible.This paper redesigned and implemented the NLM filter algorithm to fit the challenges of seismic exploration.The optimized implementation of the NLM filter is capable of processing production-size seismic data on modern clusters and is 87 times faster than the straightforward implementation of NLM.

Deep Seismic Exploration in the Taiwan Straits: The HX9 Survey Line Experiment and Preliminary Results

By using an offshore large volume air-gun seismic source, onshore seismic stations( including mobile stations and permanent stations) and ocean bottom seismometers,a deep seismic exploration experiment was carried out for the first time in the Taiwan Straits. Results show that seismic stations can receive seismic signals from the air-gun arrays of the "YANPING Ⅱ"scientific investigation ship from as far as 280 km away.Tens of thousands of high quality seismic data items were obtained successfully and different types of P-wave seismic phases were identified. A one-dimensional crustal structure model of the survey profile HX9 shows that the crustal structure,which is reflected by Pc and Pm P reflection waves from two velocity discontinuities and basement refraction wave( Pg) constitutes the basic characteristic of the crustal structure in this region. The depths of Conrad discontinuity and Moho discontinuity are respectively16. 0km- 17. 5km and 28. 0km- 29. 5km.

Study on Anti-Disturbance and High-Resolution Shallow Seismic Exploration of Active Faults in Urban Regions

The significance of detection of urban active faults and the general situation concerning detection of urban active faults in the world are briefly introduced. In a brief description of the basic principles of anti-disturbance and high-resolution shallow seismic exploration, the stress is put on the excitation of seismic sources, the performance of digital seismographs, receiving mode and conditions, geometry as well as data acquisition, processing and interpretation in the anti-disturbance and high-resolution shallow seismic exploration of urban active faults. The study indicates that a controlled seismic source with a linear or nonlinear frequency-conversion scanning function and the relevant seismographs must be used in data acquisition, as well as working methods for small group interval, small offset, multi-channel receiving, short-array and high-frequency detectors for receiving are used. Attention should be paid to the application of techniques for static correction of refraction, noise suppressing, high-precision analysis of velocity, wavelet compressing, zero-phasing of wavelet and pre-stacking migration to data processing and interpretation. Finally, some cases of anti-disturbance and high-resolution shallow seismic exploration of urban active faults are present in the paper.

Characteristics of the Zhengzhou Laoyachen Fault Revealed by Seismic Exploration Data

Exploration and research of fault activities are the fundamentals of earthquake prediction and prevention and disaster reduction. In order to determine the location, characteristics and activities of the Zhengzhon-Laoyachen fault, shallow seismic prospecting with different exploration depth across the Laoyachen fault was carried out in the northern suburbs of Zhengzhou city in 2006. The images of the subterranean structure and tectonics at depths of 30m- 6000m have been available by applying the combined methods of explosive seismic sources and vibrator seismic sources, as well as the combination of diverse observation systems with different parameters. The outcome indicates that the Laoyachen fault is a normal fault running NW and dipping NE, which offsets stratums ahead of Neogene （N）. However, no fault displacements are found in the interior stratums of Q ＋ N.

Indexes of CNPC Seismic Exploration in 1995

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Seismic analysis of the active character of the Taihang Mountain piedmont fault

The Taihang Mountain piedmont fault is a large-scale structure zone in north and east China which cross Beijing,with the NE-NNE extent spans approximately 620 km.It is very important to determine the fault zone activity due to the close relation of active structures and earthquakes.Regarding the fault activity,there are three different opinions：1） it is a large deep fault zone;2） it is an active fault zone and an earthquake structure belt;and 3） it is not an earthquake structure belt.In order to ascertain the active character of the fault,the deep tectonic setting and the activity since the Quaternary were investigated using recent seismic and drilling data to make a joint interpretation.The investigation results show that the Taihang Mountain piedmont fault is not a large lithospheric fault because the early middle Pleistocene（Q（P2）） layers are offset by the fault and the late middle Pleistocene（Q（P2）） and late Pleistocene layers are not offset by the fault.We determine that the Taihang Mountain piedmont fault in the area is not an active fault and is also not a large lithospheric fault.This study result provides important geological and geophysical data for city planning and construction in Hebei province and, especially,has great significance for seismic hazard assessment of the capital area.

Dynamic Location Method for Shallow Ocean Bottom Nodes Using the Levenberg-Marquart Algorithm

Ocean bottom node(OBN)data acquisition is the main development direction of marine seismic exploration;it is widely promoted,especially in shallow sea environments.However,the OBN receivers may move several times because they are easily affected by tides,currents,and other factors in the shallow sea environment during long-term acquisition.If uncorrected,then the imaging quality of subsequent processing will be affected.The conventional secondary positioning does not consider the case of multiple movements of the receivers,and the accuracy of secondary positioning is insufficient.The first arrival wave of OBN seismic data in shallow ocean mainly comprises refracted waves.In this study,a nonlinear model is established in accordance with the propagation mechanism of a refracted wave and its relationship with the time interval curve to realize the accurate location of multiple receiver movements.In addition,the Levenberg-Marquart algorithm is used to reduce the influence of the first arrival pickup error and to automatically detect the receiver movements,identifying the accurate dynamic relocation of the receivers.The simulation and field data show that the proposed method can realize the dynamic location of multiple receiver movements,thereby improving the accuracy of seismic imaging and achieving high practical value.

A rigorous real-time acoustic positioning method for ocean bottom seismic exploration

The conventional technique for positioning seafloor geophones in ocean bottom seismic exploration encounters several challenges,including the significant impact of outliers on positioning results,underutilization of high-precision observations,and low efficiency in real-time data processing.These issues inevitably affect the quality of seismic exploration outcomes.To address these challenges and enhance the accuracy of geophone positioning,this paper proposes a rigorous real-time acoustic positioning method for geophones based on sequential adjustment and Baarda's outlier detection approach.The proposed method comprises three key steps:grouping the original acoustic observations,constructing the intra-group acoustic positioning model,and synthesizing the positioning results across the different groups.The validity and practicality of this approach are confirmed through a simulation experiment as well as the field experiment conducted in the Bohai Sea,China.The results demonstrate that the proposed method effectively eliminates outliers in the original observations and maximizes the utilization of high-quality observations.Compared to traditional acoustic positioning methods,it significantly reduces positioning errors from meters to decimeters,and in some cases can achieve centimeter-level precision.When the sound velocity profile in the operating sea area is measured,the method can attain the posterior standard deviation at the millimeter level and positioning errors within 10 cm.When the sound velocity profile is unknown,the method can achieve the posterior standard deviation at centimeter-level and positioning errors of approximately 20 cm.

Seismic Acquisition in the Beach of the Shengli Oilfield

The beach of the Shengli oilfield, as the prospect for steady continuous development of the Shengli oilfield, has a large area, special geographic and geological conditions, and other technical difficulties so that exploration has been slow. Seismic acquisition methods in the beach area and very shallow water have been investigated and, with the introduction of new equipment, given rise to more sophisticated acquisition geometries. A series of improved seismic exploration methods in the beach area and very shallow water are established by analyzing different shot and receiver parameters. As a result, S/N ratio and resolution of seismic data have been improved significantly to identify subsurface structures, improve reservoir description, and increase reserves and production.

Complex Exploration Techniques for the Low-permeability Lithologic Gas Pool in the Upper Paleozoic of Ordos Basin

The Ordos basin is a stable craton whose late Paleozoic undergoes two sedimentary stages: from the middle- late Carboniferous offshore plain to the Permian continental river and lake delta. Sandstones in delta plain channels, delta-front river mouth bars and tidal channels are well developed. The sandstones are distributed on or between the genetic source rocks, forming good gas source conditions with widespread subtle lithologic gas pools of low porosity, low permeability, low pressure and low abundance. In recent years, a series of experiments has been done, aimed at overcoming difficulties in the exploration of lithologic gas pools. A set of exploration techniques, focusing on geological appraisal, seismic exploration, accurate logging evaluation and interpretation, well testing fracturing, has been developed to guide the exploration into the upper Paleozoic in the basin, leading to the discoveries of four large gas fields: Sulige, Yulin, Wushenqi and Mizhi.

Application and development trend of artificial intelligence in petroleum exploration and development

Aiming at the actual demands of petroleum exploration and development,this paper describes the research progress and application of artificial intelligence(AI)in petroleum exploration and development,and discusses the applications and development directions of AI in the future.Machine learning has been preliminarily applied in lithology identification,logging curve reconstruction,reservoir parameter estimation,and other logging processing and interpretation,exhibiting great potential.Computer vision is effective in picking of seismic first breaks,fault identification,and other seismic processing and interpretation.Deep learning and optimization technology have been applied to reservoir engineering,and realized the real-time optimization of waterflooding development and prediction of oil and gas production.The application of data mining in drilling,completion,and surface facility engineering etc.has resulted in intelligent equipment and integrated software.The potential development directions of artificial intelligence in petroleum exploration and development are intelligent production equipment,automatic processing and interpretation,and professional software platform.The highlights of development will be digital basins,fast intelligent imaging logging tools,intelligent seismic nodal acquisition systems,intelligent rotary-steering drilling,intelligent fracturing technology and equipment,real-time monitoring and control of zonal injection and production.